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Thread: Unicolor precision timer -- odd failure mode

  1. #1

    Join Date
    Dec 2010
    Arlington, Mass.

    Unicolor precision timer -- odd failure mode

    I have a "Unicolor Precision Timer" that I picked up a while back. It is the sort with two knobs, one labeled 1-9, the other labeled 0.1-0.9 and a "1x" and 10x" switch. They seem common enough.

    The timer seems to work, in that all functions appear to operate: the time/focus rocker switch switches power between the safe light plug and the enlarger plug, and the time button engages the enlarger for a time set by the two knobs.

    But I have discovered that it has the odd characteristic that whatever the numbers around the knobs refer to, it is not seconds. When set to "1" (and the multiplier switch to "1x"), it fires the enlarger for a little more than half a second. Higher numbers yield a similar proportion: 4 is a bit over 2 seconds, and 9 somewhere in the 4-5 second range.

    I assume this is not how it originally worked, but it seems like an odd failure mode to me. Thoughts about what's going on here? I have other timers (an old Gralab and a Time-o-lite) whose times seem fairly accurate.

    But if this is something simple I can put right, or simply a mode of operation that I've failed to understand, I'd like to know. Failing capacitor in a timing circuit? Fractured crystal? Seen this before?


  2. #2
    ic-racer's Avatar
    Join Date
    Feb 2007

    Re: Unicolor precision timer -- odd failure mode

    I repaired an Omage timer and it had only a single silicone device (which failed and was replaced.) The rest of it was simple resistors and capacitors. Pretty easy to repair.

    Click image for larger version. 

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  3. #3

    Join Date
    Dec 2010
    Arlington, Mass.

    Re: Unicolor precision timer -- odd failure mode

    Well, I can open it up and see what I see. I am capable of desoldering/resoldering, but not so great at diagnosis of circuits, I switched from EE to CS a bit too early in my education. Was hoping there was a known failure mode for these things, but not counting on it.

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